The present invention relates to a wiping device for magnetic tape cassettes, and more particularly to such a device capable of being easily mounted to and removed from a cassette for selectively achieving cleaning and/or erasing purposes.
In this application, the term "wiping device" is limited to a cleaning and/or erasing device since the present invention can be used as a cleaning device, an erasing device, or a cleaning and erasing device, depending on the mounting of a cleaning material and/or a magnet on a main body of same structure.
In the usage of a magnetic recording and reproducing apparatus, such as a video tape player/recorder or audio tape player/recorder, there is, sometimes, a need of only erasing the contents previously recorded in the magnetic tape without re-recording new contents. However, there is not an easy, cheap and satisfactory manner to achieve this purpose to data. In addition, in reproducing or recording period, the magnetic tape of the audio or video tape cassette passes through the magnetic head of a tape player/recorder or video player/recorder, and the magnetizable surface of the magnetic tape keeps contact with the magnetic head. As used in the specification, the term "magnetizable surface" is defined as one of the surfaces of the magnetic tape which contacts the magnetic head in operation. Therefore, some of the oxides and dusts on the magnetizable surface of the magnetic tape will accumulate on the magnetic head and in the vicinity of the passing path of the magnetic tape. As a result, the signals are susceptible to distortion, the sound or picture quality is reduced, and the passing path of the magnetic tape may shift. Currently, the method to avoid this problem is to clean the magnetic head with a cleaning liquid or cleaning tape after operating the machine for a period of time. However, such cleaning processes are time-consuming and inconvenient.
In the examination of the above-mentioned parent application of this CIP application, six references are cited. The references includes U.S. Pat. No. 4,285,020 issued to Sato and August 18, 1981, U.S. Pat. No. 4,639,967 issued to Bordignon on February 3, 1987, U.S. Pat. No. 4,660,115 issued to Westfall et al. on April 21, 1987, U.S. Pat. No. 4,712,148 issued to Balz et al. on December 8, 1987, U.S. Pat. No. 4,276,575 issued to Schoettle et al. on June 30, 1981, and U.S. Pat. No. 4,509,087 issued to Jager et al. on April 2, 1985. Among the references, Jager's patent, relating to a tape grounding element, is considered relevant to the parent application. Referring to Jager's FIGS. 5 and 6, Jager's patent disclosed that a resilient element 26 can be inserted from outside into the finished magnetic-tape cassette, but it also disclosed that the resilient element 26 comprises a limb 40 projecting therefrom to abut against a stop 41 fromed by a portion of the cassette wall 8, so as to prevent the resilient element 26 from being removed from the cassette (seeing Jager's FIG. 6, and lines 1 to 10, column 3 and lines 6 to 17, column 7 of Jager's specification). That is to say, Jager teaches that the resilient element can be inserted into but cannot be removed away out of the cassette from outside. This is due to the fact that the tape grounding element need not be changed by a new one even after a long-period usage, and is suitable to be permanently mounted in the cassette. This is quite different from the case of acting as an erasing or cleaning device. Moreover, the unremovable resilient element is strongly suggested by Jager, also seeing its other structures in FIGS. 7 to 15. Anyone who reads Jager's specification will by no means be implied that, in some cases, the resilient element may preferably be removalbe out of the cassette from outside.
Referring to Jager's FIGS. 5 to and 6, and FIG. 1 of this application, the arm 27 is very narrow, about one seventh of the width of the magnetic tape 7. As those skilled in the art know, the width of the magnetic tape 7 is 1/2 inch, i.e. about 1,265 cm, and thus the width of the arm 27 is about 0.18 cm. It is clear that Jager's resilient element 22 with a pad or magnet mounted on the arm 27 still cannot act as a practicable cleaning device or erasing device because it can only clean or erase the part of one seventh of the entire magnetic tape.
Furthermore, Jager's magnetic-tape cassette is a quite unique cassette, as described in the first paragraph of column 1 in Jager's text, and the structure of the cassette must be altered to mate the Jager's resilient element, seeing from Jager's FIG. 5 through FIG. 15. As those skilled in the art know, Jager's cassette is applicable only to the special video tape recorder, Model VR-2020, which are manufactured and sold by Philips Corporation, Holland, in 1980, and then stopped manufacturing before long. The magnetic-tape loading system of Jager's cassette is illustrated in FIG. 2 of this application. As seen from FIG. 3 of this application, the arm 27 always contacts the surface of the magnetic-tape 7 along a line whether or not the magnetic-tape 7 is loaded. Therefore, its erasing or cleaning effect is not satisfactory even if it is applied as an erasing or cleaning device.